Circuit breaker



Dec. 22, 1942. 1.. s. WALLE 2,306,235

\ CIRCUIT BREAKER Filed Aug. 6, 1941 2 Sheets-Sheet 1 Fig.1.

Inventor;- Ludwig S. Walle', b His Attorney.

Dec. 22, 1942. L, WALLE 2,306,235

0 IRCUI T BREAKER Filed Aug. 6, 1941 2 Sheets-Sheet 2 Invencof: T ,udwig S. Walls,

is Attorney .mounted carrier.

Patented Dec. 22, 1942 CIRCUIT BREAKER Ludwig S. Walle, Lansdowne, Pa, assignor to General Electric Company, a corporation New York Application August 6, 1941, Serial No. 405,592 is Claims. (or. 200-116) My invention relates to circuit breakers and more particularly it relates to a new and improved operating mechanism for automatic circuit breakers of the type known as branch-cira manually operable current responsive circuit breaker mechanism having only single spring means for effecting quick make, quick break and trip-free automatic circuit breaking operation.

It is a specific object of my invention to provide a mechanism of the above character which shall include means for positively opening the breaker contacts to prevent welding thereof.

In carrying out my invention in one form, I provide an operating lever pivoted at a fixed point and provided at its one end with means for pivotally supporting a movable switch member. To free end of the movable switch member I cpnnect an overcenter spring, the other end of which is anchored to the swingable end of a pivotally The carrier is normally retained in a fixed position by a latch mechanism which is actuable in. conjunction with a suitable overcurrentdevice to release the carrier. In normal manual operation the free end of the movable switch member is moved over center in toggle fashion with respect 'to the spring by means of the pivotally mounted operating lever. To insure the positive breaking of any weld which may have formed at the contacts, the switch member is arranged for manual rotation about a. normally-fixed fulcrum immediately prior to the operation of the overcenter spring. Upon the occurrence of an excessive current the pivotally mounted carrier is released by the latch mechanism and is moved by thespring so that its swingable endl moves the dad of: the spring over center .with respect to the pivotally mounted end of the movable switch member, thereby to move the switch member to circuit opening position'. -To insure positive movement'of the switch member to circuit opening position so that weld-. ing of the contacts does not occur as the spring po sses deadcen'ter, Ialso provide means on the carrier for striking the switch member with a hammer blow upon release of the carrier.

To-the attainment of the foregoing and other objects and advantages, my invention is preferably embodied in the detailed construction to be hereinafter more fully described and claimed, and is illustrated in the accompanying drawings in which Fig. 1 is a frontv view of an automatic circuit breaker embodying myinvention; Fig. 2 is a side elevation, partly in section, of the device of Fig. 1 showing the contacts and the operating mechanism in the .off position; Fig. 3 is a side view of the circuit breaker operating mechanism, partly in section, showing the mechanism in its 0113" position; Fig. 4 is a view similar to that of Fig. 3 showing the mechanism in its on position; Fig. 5 is an endview of the operating mechanism in its of! position; Fig. 6 is a view simi lar to those of Figs. 3 and 4 showing the mechanism in its automatic trip" position; and Fig.

I is a perspebtive view of the circuit breaker operating mechanism in its on position of Fig. 4.

Referring now to the drawings, one preferred form of my circuit breaker comprises a base it which is suitably formed of a molded insulating compound, and a cover ll preferably formed of similar insulating material and apertured at l2 to provide access to a suitable operating handle ii. In the three-phase form of my circuit breaker; I mount three enclosed contact chambers l4 side by side upon the base Ill. Each of the chambers it contains a movable contact l5 and a stationary contact It as shown at Fig. 2. The movable contacts in all the chambers are connected to be operated by a common rotatable operating shaft ii. The shaft I! may be insulated from the movable'contact l5 by any suitable means. By way of example I have shown the shaft ll formed of insulatingmaterial. The operating shaft I1 is connected for operation to a movable switch member or toggle arm l8 by means of a crank leverill connected to the shaft H, a bell crank 20, H connected to the movable switch arm l8 by a pin and slot connection, and a connecting rod 22 between the crank lever l9 and the arm 20 of the bell crank.

The operating mechanism itself is mounted upon a pair of supporting plates 25 and 26 which are'flxedly attached to the base ill. in upright parallel spaced relation. -A manually operable operating lever 21 is pivotally mounted intermediate its ends between the supporting plates 25, 28 by means of a fixed pivot pin 28 Preferably located near the upper ends of the plates 25, 26. The operating lever 2! carries at its upper end the operating handle I3 and is formed to provide beneath the pivot pin 28 a substantially triangular aperture 29 for the purpose which will be more fullydescribed hereinafter. As is most clearly shown in Fig. '7 the supporting plates 25 and 25 are provided with substantially rectangular aligned apertures 30 and 3|, respectively,

adjacent the aperture 29 in the operating lever The movable switch arm I8 is pivotally connected at one end to the lower end of the operating lever 21 by a movable pivot pin. In the form shown the operating lever 21 comprises a pair of plates connected together in parallel spaced relation and the movable switch arm I8 is pivotally mounted between these plates. The

in a predetermined fixed position by a .latch lever 35 which is mounted upon the fixed pivot 28. The upper end of the carrier 33 is formed to provide a shoulder 40 which normally engages a roller 4| on the latch lever 35 to hold the carrier 33 in fixed position. The latch lever 35 is preferably biased to latching position by any suitable means such as a cantilever leaf spring 4Ia. The upper .end of the carrier 33 extends between the apertured plates comprising the op erating lever 21 and carries a transverse in 42 which projects through the aperture 29 in the operating lever and beyond the side supporting plates 25, 26 through their respective apertures and 3I. A similar transverse pin 43 is connected to the free end of the movable switch member I8. Between the outer ends of the pins 42 and 43 are connected a pair of overcenter operating springs 44, 45. As illustrated at Fig. the transverse pin 43 also serves to connect the free end of the movable switch member I8 to the slotted bell crank arm 2|.

Any suitable means may be provided for ac-' tuating the latch lever to disengage the roller H from the shoulder upon the occurrence of an excessive current. Referring now to the drawings, particularly to Fig. 2, I have illustrated one such means as a spring pressed striker 45 adapted to be released by a current responsive element such as a bimetallic strip 46a and to strike the projecting end of the latch lever 35 with a hammer blow, thereby to disengage the roller 4| from the shoulder 40.

In circuit breakers which are tripped by an over-center spring mechanism upon the occurrence of an excessive current, welding of the contacts frequently occurs because of the fact that during the contact opening operation a point is reached where the contact pressure is zero. At this point in the operation even relatively small currents will frequently cause welding of the contacts. In order to overcome this difficulty, my. invention includes meansfor delivering to the switch operating member a hammer blow in automatic tripping operation. Preferably this hammer blow is administered before the mechanism has reached dead center and therefore before the contact pressure has been reduced to zero,'thereby to drive the switch member positively and rapidlythrough the dead center position with the force of the blow. For this purpose I provide the swingable carrier 33 with a projection 41 intermediate its ends and positioned to strike the movable switch member I8 when the carrier is released in automatic tripping operation. The projection 41 extends sufficiently far to engage the toggle arm I8 before the upper end of the carrier has moved the springs 44, 45 over center with respect to the pivot pin heads 32. v

In operation, when the circuit breaker is in the oil' position shown at Figs. 2 and 3, it may be moved to the on position by rotating the operating lever 21 about. the fixed pivot 28 to the position shown in Fig. 4. By this movement the lower end of the operating lever 21 and the pivot pin are moved over center with respect to the operating springs 44, 45 so that the free end of the movable switch arm I8 is now biased to the left instead of to the right as viewed in the drawings. During'this operation the upper ends of the overcenter springs 44, 45 remain fixed with respect to the supportingplates 25, 26, since the swingable carrier 33 is latched in fixed position.

Also, the movement of the switch arm I8 is limited and its off position is defined by en-- 1 gag'ement of the transverse pin 43 with the rear sides'of the aligned apertures Mane-3| in the supporting plates 25 and 26, as shown atFig. 3.

To insure a'positive contact, the contact structure itself limits and defiriesythe on position of the mechanism. The manual movement of the breaker mechanism from the on position of Fig. 4 to the oil position of Fig. 3 is simply the reverse of the movement just described. During the latter movement the pin 42 serves as a stop engaging the'forward sides of the aper tures 30 and 3I to prevent counterclockwise rotation of the carrier 33, as viewed in Figs. 3 and 4. Thus, in manual operation of the switch, it

will be evident that the springs 44, '45 act as simple overcenter springs having their upper ends fixedwith respect to the support, while the toggle arm has one end attached to the springs and the other end movable over center with respect thereto by means of the operating lever 21.

The projection 41, previously described in connection with automatic tripping operation, also acts as a fixed fulcrum for the toggle arm I8 7 during manual opening operation, thereby to provide a positive opening and the breaking of any weld which may have formed at the contacts.

Referring particularly to Fig. 4, it will be observed that the outer end of the projection 41 on the normally fixed carried 33 lies onor very close to a line extending between the pivot pins 42 and 43. Consequently, immediately prior to the passage of the pivot pin heads 32 overcenter with respect to the springs 44, 45, the toggle arm I8 engages the projection 41 and pivots upon it as a fulcrum.

It will be evident that during the instant when the switch arm I8 is pivoting upon the projection 41 the pivot pin 43, and consequently the bell crank 20, 2| and the operating shaft II, are being positively moved by means of the operating handle I3. The pivoting of the switch arm'IB about the projection 41 also accelerates the overcenter travel of the pivot pin heads 32, since the two ends of the switch arm are being moved in opposite directions. As soon as the overcenter travel is complete and any welds at the contacts are broken, the springs 44, 45 rapidly move the switch arm. I8 to the position shown at Fig. 3.

Upon the occurrence of an excessive current the current responsive mechanism releases the striker 46 for actuation into engagement with the latch lever 35, thereby to disengage the roller 4| from the shoulder 40. This action will of course take place only when the mechanism is in its on position shown in Fig. 4. From Fig. 4 it will be observed that the overcenter springs 44,

45 not only bias the toggle arm l8 to the on position but also bias the swingable carrier 33 for clockwise rotation about the fixed pivot 34 as viewed in the drawings. 'I'hus, upon disengagement of the shoulder 40 and the roller 4|, the carrier 33 will rotate in a clockwise direction about the fixed pivot 34 under the influence of springs 44, 45. In this movement of the swingable carrier 33 the upper end of the carrier and the transverse pin 42, which forms an anchorage for the upper ends of the springs 44, 45, will be moved to the right, as viewed in the drawings, and over center with respect to the movable pivot pin, thereby to bias the free end of the switch arm |8 toward the right as shown at Fig. 6. Referring again to Fig. 4, it will also be observed that during the clockwise rotation of the swingdescribed, the transverse pin 42 lies in the lower right corner of the triangular aperture 29 in the operating lever 21. It will be observed by comparison of Figs. 4 and 6 that the operating handle 21 does not move during the automatic tripping operation. This trip-free feature of my circuit breaker results from the fact that the transverse pin 42 is positioned within the triangular aperture 29 at the lower end of the operating handle. In, automatic operation the movement of the swingable carrier 33 causes the transverse pin 42 to move from the upper left corner of the triangular aperture 29 to the lower right corner, as viewed in the drawings. In the trip" position of the circuit breaker as shown in Fig. 6, the transverse pin 42 engages the lower right hand corner of the triangular aperture 29 to limit the movement of the carrier 33. In this respect attention is directed to the fact that the sides of the aligned substantially rectangular apertures 30 and 3| are preferably notched at 50 and respectively, to accommodate the pin 42. Without such notches the pivot pin heads 32 and the transverse pins 42 and 43 would be positioned in a substantially straight line along the sides of the apertures 30 and 3| when the breaker is in its trip position. By notching the apertures 30 and 3| at 50 and 5| the pin 42 is allowed to move beyond dead center thereby to impart to the switch arm IS a substantial switch opening bias. (Fig. 6). It will be understood, ofcourse, that, while it is desirable to notch the supporting plates 25 and 26 as described so that the pins 42 can move beyond dead center, it is not material whether the pin 42 in its final position engages the edge of the aperture 29 or the notches 50 and 5| or both.

To reset the breaker mechanism after it has taken up its "trip position of Fig. 6, the operating lever 21 must be rotated in a clockwise direction as viewed in the drawings about the fixed pivot 28. By this movement the movable pivot pin at the lower end of the operating lever 21 is brought into engagement with the swingable carrier 33 at a point intermediate the transverse pin 42 and the projection 41, thereby to move the carrier 33 in a counter-clockwise direction against the bias of the operating springs 44, 45. During this resetting movement the movable pivot pin is not moved over center with respect to the operating springs 44, 45 so that the free end of the movable switch member l8 remains biased, and in fact is increasingly biased to its switch opening position. When the carrier 33 has been moved in a counter-clockwise direction sufliciently far to permit the roller 4| to talllnto engagement with the shoulder 40 under the influence of the leaf spring 4|a, the mechanism will be in the "ofi position shown at Fig. 3 and may now. be operated manually as previously described. Certain of the broader features of the switch mechanism hereindisclosed are claimed in a copending application of W. L. Butler, Serial No. 390,644, filed April 28, 1941, and assigned to the same assignee as the instant application.

While'I have shown, and described a preferred form of my invention by way of illustration, many modifications will occur to those skilled in the art. I therefore wish to have it understood that I intend by the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A circuit breaker comprising cooperating switch contacts, a pivotally mounted operating lever, a movable switch member having free end connected to one of said contacts an another end pivotally connected to said operating lever, a pivoted carrier, latch means normally holding said carrier in a predetermined fixed position, an overc'enter spring connected between said free end of said switch member and said carrier, said carrier being arranged when released by said latch means to move one end of said spring overcenter with respect to said switch member thereby to bias said switch member to a circuit opening position, and means operable upon release of said carrier by said latch to strike said switch member thereby positively to move said switch member to open said contacts.

2. A circuit breaker comprising a support, cooperating switch contacts, a movable switch arm operatively connected to one of said contacts, an operating lever pivotally supported at a fixed point in' said support and having one end pivotally connected to one end of said movable switch arm, a swingable carrier pivoted at a second fixed point in said support, latch means for normally engaging said carrier to hold said carrier normally in a predetermined fixed position, an overcenter spring connected between the other end of said movable switch arm and the swingable end of said carrier for biasing said carrier to move said spring to a position to bias said movable switch arm to a switch opening position,

and means operative in conjunction with said carrier to strike said movable switch arm upon release of said carrier thereby positively to movev end pivotally connected to one end of said movable switch arm, a swingable carrier pivotally mounted at a second fixed point in said support, latch means for normally engaging the swingable end of said carrier to hold said carrier normally in a predetermined fixed position, an overcenter spring connected between the other end of said movable switcharm and the swingable end of said carrier for biasing said carrier to move said spring to a position tov bias said movable switch arm to a switch opening position, and means responsive to the current passing through-said contacts for'operating said latch means to release said carrier, said carrier being formed to provide a portion arranged to strike said movable switch arm upon release of said carrier thereby positively to move said switch arm with respect to said spring.

4. An automatic circuit breaker comprising a support, cooperating switch contacts, a manually operable operating lever pivotedv at a fixed point in said support, one end of said operating lever being provided with an aperture and the other end of said lever being provided with an operating handle, a swingable carrier pivoted at one end in said support and provided at the other end with a transverse pin extending through said aperture, latch means arranged to engage said other end of said carrier normally to hold said carrier in a predetermined fixed position, a movable toggle arm having one end pivotally conovercenter nected to said one end of said operating lever, means for connecting. the other end of'said toggle arm to one of said contacts, an overcenter spring connected between said transverse pin and said other end of said toggle arm for biasing said carrier to move said spring to a position to bias said toggle arm to a switch opening position, and means responsive to the current passing through said contacts for actuating said latch to release said carrier, said carrier being formed to provide a projection arranged to strike said toggle arm a hammer blow upon release of said carrier thereby positively to move said toggle arm to a switch opening position and to prevent welding of said contacts.

5. An; automatic circuit breaker comprising a support, cooperating switch contacts, a carrier pivotally mounted upon said support, latch means engaging said carrier normally to .hold said carrier in a predetermined fixed position, a movable switch arm having a free end operatively connected to one of said contacts, an overcenter -spring connected between said carrier and said switch arm, a pivoted operating lever, pivotal means for connecting said switch arm at its otherv end to said operating lever for movement of said other endof said switch arm overcenter with respect to said'spring, and means responsive to contacts, an overcenter spring connected between said swingable end of said carrier and said free end of said toggle arm, an operating lever pivotally mounted upon said support, pivotal means for connecting the other end of said toggle arm to said operating lever for movement over center with respect to said spring thereby to bias said free end of said toggle arm selectably to switch opening and switch closing positions, stop means associated with said toggle arm to limit its movement and define said switch opening and switch closing positions, and means responsive to the current passing through said contacts for actuating said latch means to release said carrier for rotation under the influence of said overcenter spring thereby to move said spring over center with respect to said pivotal means, said carsupporting plates on a fixed pivot, one end of said operating lever lying substantially wholly between said plates and being provided with an aperture, a movable switch arm having one end pivotally connected to said one end of said operating lever, a swingable carrier mounted between said plates and pivotally supported upon said plates at a fixed point, a transverse pin connected to the ,swingable end of'said carrier and extending through said aperture, a latch lever mounted upon said fixed pivot and biased normally to engage the swingable end of said carrier to hold said carrier normally in a predetermined fixed position, an overcenter spring connected between the other end of said movable switch arm and said transverse pin for biasing said carrier to move said spring to a position to bias said switch arm to a switch opening position, and means responsive to the current passing through said contacts for actuating said latch lever to release said carrier, said carrier being formed to provide a projection intermediate its ends arranged to upon said base in upright parallel spaced relation, said supporting plates being provided with aligned aperturesya manually operable operatthe current passing through said contacts for actuating said latch means to release said carrier for movement under the influence of said overcenter spring thereby to move said spring overcenter with respect to said pivotal means, said 7 a operating switch contacts, a support, a. carrier pivotally mounted upon said support, latch means engaging a swingable end of said carrier normally. to hold said carrier in a predetermined fixed position, a movable toggle arm having a free end operatively connected to one of said ing lever mounted between said plates upon a fixed pivot, the lower end of said operating lever engageable with the sides of said aligned apertures to define a switch open position of said switch arm, a swingable carrier pivotally mounted between said supporting plates, the swingable end of said carrier being formed to provide a latch engaging shoulder and having connected thereto a second transverse pin extending through said triangular aperture and through saidaligned apertures, a latch lever pivotally mounted upon said fixed pivot, said latch lever being biased to a normal position in engagement with said shoulder thereby to hold said carrier normally in a predetermined fixed position, a pair of, overcenter springs connected between saidv first and second transverse pins, means responsive'to the current passing through said contacts to operate said latch lever to release said carrier, and means formed upon said carrier intermediate its ends to strike said movable switch arm a hammer blow upon release of said carrier thereby positively to move said switch arm overcenter with respect to said spring to open said contacts.

9. A circuit breaker comprising cooperating switch contacts, a movable switch member operatively connected to one of said contacts, a pivoted operating lever providing means for pivotally supporting one end of said movable switch member, a pivoted carrier, latch means normally holding said carrier in a predetermined fixed position, an overcenter spring connected between the free end of said switch member and said carrier, and means operable upon movement of said operating lever to engage said switch member as'a fulcrum intermediate its ends thereby to insure a positive opening of said contacts.

10. A circuit breaker comprising a support, cooperating switch contacts, a movable switch arm operatively connected to one of said contacts, a manually operable operating lever pivotally supported at a fixed point in said support and having one end pivotally connected to one end of said movable switch arm, a swingable carrier pivoted at a second fixed pointin said support, latch means for normally engaging said carrier to hold said carrier normally in 'apredetermined fixed position, an overcenter spring connected between the other end of saidmovable switch arm and the swingable end of said carrier for biasing said. carrier to move said spring to a position to bias said movable switch arm to a switch opening position, said operating lever being arranged to move said one end of said movable switch arm overcenter with respect to said spring thereby to open and to close said contacts, and means op erative in conjunction with said carrier upon movement of said operating lever in a switchopening direction to engage said movable switch arm as a fulcrum prior to movement of said one end of said movable switch'arm overcenter with respect to said spring, whereby said contacts are separated by a positive linkage prior to operation of said overcenter spring.

11. An automatic circuit breaker comprising a support, cooperating switch contacts, a movable switch arm operatively connected to one of said contacts, a manually-operable operating lever pivotally supported at a fixed point in said support and having one end pivotally connected to latch means to release said carrier, said carrier being formed to. provide a portion arranged to engage said movable switch arm upon manual movement oflsaid operating lever or upon release of said carrier by said latch means.

12. An automatic circuit breaker comprising a support, cooperating switch contacts, a manually operable operating lever pivoted at a fixed point in said support, one end of said operating lever being provided with an aperture and the other end of said lever being provided with an operating handle, a swingable carrier pivoted at one end in said support and provided at the other end with a transverse pin extending through said aperture, latch means arranged to engage said other end of said carrier normally to hold said carrier in a predetermined fixed position, a movable toggle arm having one end pivotally connected at one end of said operating lever, means 'for connecting the other end of said toggle arm to one of said contacts, an overcenter spring connected between said transverse pin and said free end of said toggle arm for biasing said carrier to move said spring to a position to bias said toggle arm to a switch opening position, and means responsive to the current passing through said contactsfor actuating said latch to release said carrier, said carrier being formed to provide a projection arranged to engage said switch arm and to serve as a fulcrum therefor upon manual movement of said operating lever thereby positively to move said contacts to open position and to break any weldformed between said contacts.

13. A circuit breaker comprising cooperating switch contacts, a pair of supporting plates mounted in parallel spaced relation, said supporting plates being provided with aligned apertures, a manually operable operating lever mounted between said supporting plates on a fixed pivot, one end of said operating lever lying substantially wholly between said plates and being provided with a third aperture, a movable switch arm having one end pivotally connected to said one end of said operating lever, a swingable carrier mounted between said plates and pivotally supported upon said plates at a fixed point, a transverse pin connected to the swingable end of said carrier and extending through said aligned apertures and said third aperture, a latch lever mounted upon said fixed pivot and biased normally to engage the swingable end of said carrier to provide a projection intermediate its ends to engage said switch arm intermediate its end 14. A trip-free circuit breaker comprising a. l

stationary contact, a movable contact, a movable switch member for operating said movable contact between closed and open circuit positions,

a carrier member, a spring having one end connected to said carrier member and its other end connected'to said switch member, latch means normally holding said carrier member in a predetermined position against the force applied by said spring, and means responsive to the current passing through said contacts for actuating said latch means to release said carrier member, said carrier member being arranged when released to move said one end of said spring overcenter with respect to said switch member and to engage said switch member thereby to move said switch memberto its open circuit position.

15. A trip-free circuit breaker comprising a stationary contact, a movable contact, a movable switch member for operating said movable contact between closed and open circuit positions,

a carrier member, a spring having one end connected to said carrier member and its other end connected to said switch member, latch means normally holding said carrier member in a presition, and means for moving said switch member about said carrier as a pivot to its open circuit position.

16. A circuit breaker comprising a stationary contact, a movable contact, a pivoted switch member having a pivoted end and airee end movable to operate said movable contact between closed and open circuit positions, a pivoted carrier member, a spring having one end connected to said carrier member and its other end connected to said free end of said switch member, latch means normally holding said carrier member in a predetermined position against the force applied by said spring, means responsive to the current passing through said contacts for actuating said latch means to release said carrier member, means for moving said pivoted end of said switch member thereby to cause said spring to snap said free end from one position to another, and a projection on said carrier member arranged when said carrier member is released by said latch means to engage said switch member and to move said switch member to its open circuit position, said projection being also arranged to be engaged by said switch member and to form a pivot therefor when said pivoted end of said switch member is moved to operate said switch member to its open circuit position.

LUDWIG S. WALLE. 

